Spin-torque magnetic memory devices store information by controlling the resistance across a magnetic tunnel junction (MTJ) such that a read current through the magnetic tunnel junction results in a voltage drop having a magnitude that is based on the state of the magnetic tunnel junction stack. The resistance in each magnetic tunnel junction can be varied based on the relative magnetic states of the magnetoresistive layers within the magnetic tunnel junction stack. In such memory devices, there is typically a portion of the magnetic tunnel junction stack that has a fixed magnetic state and another portion that has a free magnetic state that is controlled to be either of two possible states relative to the portion having the fixed magnetic state. Because the resistance through the magnetic tunnel junction changes based on the orientation of the free portion to the fixed portion, information can be stored by setting the orientation of the free portion. The information is later retrieved by sensing the orientation of the free portion. Such magnetic memory devices are well known in the art.
There is a need for memory architectures and the access circuitry used to store and retrieve data from magnetic tunnel junction based memory cells that allow for accurate storage and retrieval of information with short access times.